Transparent recording sheets

Abstract: Disclosed is a substantially transparent recording sheet which comprises (a) a substantially transparent substrate; (b) a binder polymer coated on the substrate; and (c) particles of an antistatic component, said particles being present on at least the surface of the binder polymer coating.

Description: The present invention is directed to transparent sheets suitable for receiving images. More specifically, the present invention is directed to transparent recording sheets particularly, but not exclusively, suitable for use in electrophotographic imaging processes. Materials for transparencies, coatings for recording sheets and various imaging processes are disclosed in the patent literature, see for example US-A-s: 5,118,570; 5,006,407; 5,145,749; 4,526,847; 3,619,279; 3,561,337; 3,493,412; 3,488,189; 4,956,225 and 4,997,697. While those known materials and processes are suitable for their intended purposes, a need remains for improved transparent recording sheets. In addition, a need remains for transparent recording sheets particularly suitable for use in conjunction with electrostatic toners. Further, there is a need for transparent recording sheets containing anti-static components and exhibiting improved adhesion of an electrostatic toner image to the recording sheet surface. Additionally, there is a need for transparent recording sheets containing anti-slip components and exhibiting improved adhesion of an electrostatic toner image to the recording sheet surface. There is also a need for transparent recording sheets wherein both an anti-static component and an anti-slip component are contained in a single coating layer of the sheet. Further, there is a need for transparent recording sheets wherein the sheets exhibit superior transparency characteristics subsequent to formation of an image thereon. EP-A-444,950 describes a transparent recording sheet coated with a mixture comprising a cellulose and a non-cellulosic component. An object of the present invention is to strive to provide transparent recording sheets with the above advantages. Accordingly, the present invention provides a recording sheet and an imaging process in accordance with any one of the appended claims. In a preferred embodiment the transparent recording sheets are particularly suitable for use in conjunction with electrostatic toners. In various embodiments of the present invention transparent recording sheets are provided containing anti-static and/or anti-slip components and exhibiting improved adhesion of an electrostatic toner image to the recording sheet surface. In one embodiment of the present invention transparent recording sheets are provided wherein the sheets exhibit superior transparency characteristics subsequent to formation of an image thereon. In one aspect of the present invention there is provided a transparent recording sheet which comprises (a) a substantially transparent substrate; (b) a binder polymer coated on the substrate; and (c) particles of an antistatic component, said particles being present on at least the surface of the binder polymer coating. The invention will be described further, by way of example, with reference to the accompanying description below. The recording sheets of the present invention comprise a substantially transparent substrate or base sheet having a coating on one or both surfaces thereof. Any suitable substantially transparent substrate can be employed. Examples include polyesters, including Mylar™, available from E.I. Du Pont de Nemours & Company, Melinex™, available from Imperial Chemicals, Inc., Celanar™, available from Celanese Corporation, polycarbonates such as Lexan™, available from General Electric Company, polysulfones, such as those available from Union Carbide Corporation, polyether sulfones, such as those prepared from 4,4'-diphenyl ether, such as Udel™, available from Union Carbide Corporation, those prepared from disulfonyl chloride, such as Victrex™, available from ICI Americas Incorporated, those prepared from biphenylene, such as Astrel™, available from 3M Company, poly (arylene sulfones), such as those prepared from crosslinked poly(arylene ether ketone sulfones), cellulose triacetate, polyvinylchloride cellophane, polyvinyl fluoride, polyimides, and the like, with polyester such as Mylar™ being preferred in view of its availability and relatively low cost. The substrate can be of any effective thickness. Typical thicknesses for the substrate are from about 50 to about 500 microns, and preferably from about 100 to about 125 microns, although the thickness can be outside these ranges. Contained on one or both surfaces of the base sheet is a coating. This coating can be either coated directly onto the base sheet or coated onto another layer of material coated onto the base sheet previously, such as an antistatic layer, an anticurl layer, or the like. In one embodiment of the present invention, the coating comprises a binder polymer but contains no particles of an antistatic component; the antistatic particles are subsequently coated onto the binder layer. In another embodiment of the present invention, the coating comprises both a binder and particles of an antistatic component. In the embodiment of the present invention wherein the substrate is coated with a mixture of binder and antistatic particles, the binder and antistatic particles are dispersed together in a solvent, preferably a polar solvent, such as methanol or the like, which is a relatively good solvent for the binder but a relatively poor solvent for the antistatic particles. Typically, the solvent is present in an amount of from about 50 to about 95 percent by weight, the binder is present in an amount of from about 2 to about 25 percent by weight, and the antistatic material is present in an amount of from about 1 to about 10 percent by weight, although the amounts can be outside these ranges. The dispersion is then applied to the substrate and the substrate is dried to yield the recording sheet. In the embodiment of the present invention wherein the substrate is first coated with the binder and the binder is then coated with the antistatic particles, the binder is first coated onto the substrate by dispersing or dissolving it in a solvent, such as water, ethanol, methanol, acetone, dichloromethane, toluene, or the like, which is a relatively good solvent for the binder. Typically, the solvent is present in an amount of from about 50 to about 99 percent by weight and the binder material is present in an amount of from about 1 to about 50 percent by weight, although the relative amounts can be outside these ranges. The substrate is then dried. Subsequently, the antistatic particles are dispersed in a solvent, such as water, ethanol, methanol, acetone, or the like, which is a relatively good solvent for the antistatic material but a relatively poor solvent for the binder material. Typically, the solvent is present in an amount of from about 75 to about 99 percent by weight and the antistatic material is present in an amount of from about 1 to about 25 percent by weight, although the relative amounts can be outside these ranges. This solution or dispersion is then coated or sprayed onto the binder layer and dried to yield the recording sheet. The terms "relatively good solvent" and "relatively poor solvent", as used herein, generally refer to the polymer solubility characteristics in a given solvent as related to viscosity, molecular weight, concentration, and temperature. At any given temperature, the viscosity of a solution of a polymer is related to the polymer's molecular weight by the Mark-Houwink-Sakurada equation as follows: |η| = kM α wherein η is the intrinsic viscosity of the polymer in the solvent, k is a constant specific to each polymer/solvent combination, and M is the polymer molecular weight. The value of α is determined by dissolving a polymer with a given molecular weight in a solvent at a given temperature and at a selected concentration, measuring the viscosity of the solution, dissolving the same polymer in the same solvent at the same temperature at additional, different concentrations, measuring the viscosity of each additional solution, and plotting concentration versus viscosity. Extrapolating to zero concentration yields the intrinsic viscosity of the polymer at that molecular weight in the particular solvent at the given temperature. This process is then repeated at different molecular weights of the polymer to obtain a series of values for intrinsic viscosity at different molecular weights. Plotting intrinsic viscosity versus molecular weight then yields a line with a slope α. The value of k can then be calculated for the polymer/solvent combination. For the purposes of the present invention, a solvent generally is a "relatively good solvent" for the selected material when the value of α is greater than 0.5 and generally is a "relatively poor solvent" for the selected material when the value of α is 0.5 or less. Further information regarding polymer solubility characteristics is disclosed in, for example, Polymer Handbook , 2nd Edition, J. Brandrup and E.H. Immergut, Eds., section 4, pages 1 et seq., John Wiley & Sons (1975), the disclosure of which is totally incorporated herein by reference. In embodiments wherein the binder and the antistatic material are present in a single layer, this layer can be of any desired or effective thickness. Typically, this single layer is from about 3 to about 10 microns in thickness, although the thickness can be outside this range. In embodiments wherein the binder and the antistatic material are present in two layers, each layer can be of any desired or effective thickness. Typically, the binder layer is from about 1 to about 10 microns in thickness and the antistatic particle layer is from about 1 to about 5 microns in thickness, although the layer thicknesses can be outside these ranges. The antistatic particles preferably are of an average particle diameter of less than about 5 micron, with the particle size typically being from about 0.5 to about 5 microns, and more preferably less than about 1 micron. Particles of the desired particle diameter can be obtained commercially. In addition, particles of the desired particle diameter can be obtained by recrystallization of the antistatic material from a solvent or by mechanical pulverization. For example, carboxymethyl cellulose, when dissolved in water and precipitated in methanol, or when dissolved in water and spray dried, provides dried particles of less than 1 micron in diameter; particles of carboxymethyl cellulose can also be obtained in average particle diameters of 2 to 3 microns by pulverizing or powdering processes such as ball milling. Preferably, the index of refraction of the antistatic material matches the index of refraction of the binder material as closely as possible, preferably to within ±0.01, and more preferably to within ±0.005, although the indices of refraction of the two materials may differ by more than these amounts. The antistatic material has a melting point of about 70°C or less, and more preferably has a melting point of about 50°C or less. When the index of refraction of the binder material and the index of refraction of the antistatic material are within the above indicated values, the recording sheet is substantially transparent, both in the embodiment wherein the sheet is prepared by coating the substrate with a mixture of binder and antistatic particles and in the embodiment wherein the sheet is prepared by coating the substrate with the binder and subsequently coating the binder with the antistatic particles. When the index of refraction of the binder material and the index of refraction of the antistatic material are not within the above indicated values, the recording sheet may initially lack the desired degree of transparency; however, with the melting point of the antistatic material less than about 70°C, the antistatic particles will tend to melt when the recording sheet is passed through the fusing system of an imaging device employing an electrostatic toner, and the resulting imaged sheet will generally exhibit the desired degree of transparency. For the embodiment of the present invention wherein a mixture of a binder polymer and antistatic particles are coated onto the substrate in a single layer, and for embodiments wherein it is desired to match the index of refraction of the antistatic particles as closely as possible to the index of refraction of the binder material, preferred optional antistatic particles include polysaccharides and salts of polysaccharides. Examples of optional antistatic materials particularly preferred for the embodiment of the invention wherein a mixture of a binder polymer and antistatic particles are coated onto the substrate in a single layer, and for embodiments wherein it is desired to match the index of refraction of the antistatic particles as closely as possible to the index of refraction of the binder material, include hydrophilic polysaccharides and their modifications, such as (1) starch (such as starch SLS-280, available from St. Lawrence starch), (2) cationic starch (such as Cato-72, available from National Starch), (3) hydroxyalkylstarch, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from about 1 to about 20 carbon atoms, and more preferably from about 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, or the like (such as hydroxypropyl starch (#02382, available from Poly Sciences Inc.) and hydroxyethyl starch (#06733, available from Poly Sciences Inc.)), (4) gelatin (such as Calfskin gelatin #00639, available from Poly Sciences Inc.), (5) alkyl celluloses and aryl celluloses, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, and even more preferably from 1 to about 7 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, and the like (such as methyl cellulose (Methocel AM 4, available from Dow Chemical Company)), and wherein aryl has at least 6 carbon atoms and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 6 to about 20 carbon atoms, more preferably from 6 to about 10 carbon atoms, and even more preferably about 6 carbon atoms, such as phenyl, (6) hydroxy alkyl celluloses, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, or the like (such as hydroxyethyl cellulose (Natrosol 250 LR, available from Hercules Chemical Company), and hydroxypropyl cellulose (Klucel Type E, available from Hercules Chemical Company)), (7) alkyl hydroxy alkyl celluloses, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, or the like (such as ethyl hydroxyethyl cellulose (Bermocoll, available from Berol Kem. A.B. Sweden)), (8) hydroxy alkyl alkyl celluloses, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like (such as hydroxyethyl methyl cellulose (HEM, available from British Celanese Ltd., also available as Tylose MH, MHK from Kalle A.G.), hydroxypropyl methyl cellulose (Methocel K35LV, available from Dow Chemical Company), and hydroxy butylmethyl cellulose (such as HBMC, available from Dow Chemical Company)), (9) dihydroxyalkyl cellulose, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like (such as dihydroxypropyl cellulose, which can be prepared by the reaction of 3-chloro-1,2-propane with alkali cellulose), (10) hydroxy alkyl hydroxy alkyl cellulose, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like (such as hydroxypropyl hydroxyethyl cellulose, available from Aqualon Company), (11) halodeoxycellulose, wherein halo represents a halogen atom (such as chlorodeoxycellulose, which can be prepared by the reaction of cellulose with sulfuryl chloride in pyridine at 25°C), (12) amino deoxycellulose (which can be prepared by the reaction of chlorodeoxy cellulose with 19 percent alcoholic solution of ammonia for 6 hours at 160°C), (13) dialkylammonium halide hydroxy alkyl cellulose, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like, and wherein halide represents a halogen atom (such as diethylammonium chloride hydroxy ethyl cellulose, available as Celquat H-100, L-200, National Starch and Chemical Company), (14) hydroxyalkyl trialkyl ammonium halide hydroxyalkyl cellulose, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like, and wherein halide represents a halogen atom (such as hydroxypropyl trimethyl ammonium chloride hydroxyethyl cellulose, available from Union Carbide Company as Polymer JR), (15) dialkyl amino alkyl cellulose, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like, (such as diethyl amino ethyl cellulose, available from Poly Sciences Inc. as DEAE cellulose #05178), (16) carboxyalkyl dextrans, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and the like, (such as carboxymethyl dextrans, available from Poly Sciences Inc. as #16058), (17) dialkyl aminoalkyl dextran, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like (such as diethyl aminoethyl dextran, available from Poly Sciences Inc. as #5178), (18) amino dextran (available from Molecular Probes Inc), (19) carboxy alkyl cellulose salts, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like, and wherein the cation is any conventional cation, such as sodium, lithium, potassium, calcium, magnesium, or the like (such as sodium carboxymethyl cellulose CMC 7HOF, available from Hercules Chemical Company), (20) gum arabic (such as #G9752, available from Sigma Chemical Company), (21) carrageenan (such as #C1013 available from Sigma Chemical Company), (22) karaya gum (such as #G0503, available from Sigma Chemical Company), (23) xanthan (such as Keltrol-T, available from Kelco division of Merck and Company), (24) chitosan (such as #C3646, available from Sigma Chemical Company), (25) carboxyalkyl hydroxyalkyl guar, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like (such as carboxymethyl hydroxypropyl guar, available from Auqualon Company), (26) cationic guar (such as Celanese Jaguars C-14-S, C-15, C-17, available from Celanese Chemical Company), (27) n-carboxyalkyl chitin, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like, such as n-carboxymethyl chitin, (28) dialkyl ammonium hydrolyzed collagen protein, wherein alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like (such as dimethyl ammonium hydrolyzed collagen protein, available from Croda as Croquats), (29) agar-agar (such as that available from Pfaltz and Bauer Inc), (30) cellulose sulfate salts, wherein the cation is any conventional cation, such as sodium, lithium, potassium, calcium, magnesium, or the like (such as sodium cellulose sulfate #023 available from Scientific Polymer Products), and (31) carboxyalkylhydroxyalkyl cellulose salts, wherein each alkyl has at least one carbon atom and preferably wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl and the like, and wherein the cation is any conventional cation, such as sodium, lithium, potassium, calcium, magnesium, or the like (such as sodium carboxymethylhydroxyethyl cellulose CMHEC 43H and 37L available from Hercules Chemical Company), and the like, as well as blends or mixtures of any of the above. Any mixtures of the above antistatic materials in any relative amounts can be employed. The antistatic particles can comprise blends of two or more different materials. In addition, particles of one material or blend of materials can be admixed with particles of another material or blend of materials in the recording sheets of the present invention. Preferred antistatic materials include alkane amines and cationic quaternary salts of ammonia, phosphorus, pyridine, imidazoline, and the like, particularly those which are soluble in fast evaporating solvents, such as methanol or acetone. Examples of suitable antistatic materials particularly preferred, include (1) benzyl dimethyl tetradecyl ammonium chloride dihydrate (mp 63 - 65°C) (Aldrich 29,279-6), (2) benzyl dimethyl stearyl ammonium chloride monohydrate (mp 67 - 69°C) (Aldrich 22,901-6), (3) cetyl pyridinium bromide monohydrate (mp 66 - 68°C) (Aldrich 28,531-5), (4) dodecyl pyridinium chloride monohydrate (mp 66 - 70°C) (Aldrich 27,860-2), (5) hexadecyl tributyl phosphonium bromide (mp 57 - 60°C) (Aldrich 27,620-0), (6) 1,12-diaminododecane (mp 69°C) (Aldrich D1,640-1), (7) stearyl tributyl phosphonium bromide (mp 70°C) (Aldrich 29,303-2), (8) benzyl dodecyl dimethyl ammonium bromide (mp 46-48°C) (Aldrich 28,088-7), (9) tetrabutyl ammonium chloride hydrate (mp 44°C) (Aldrich 34,585-7), (10) 1,8-diamino octane (mp 50°C) (Aldrich D2,240-1), (11) benzyl cetyl dimethyl ammonium chloride monohydrate (mp 62 - 64°C) (Aldrich 22,900-8), and the like, as well as blends or mixtures of any of the above. Any mixtures of the above antistatic materials in any relative amounts can be employed The antistatic particles can comprise blends of two or more different materials. In addition, particles of one material or blend of materials can be admixed with particles of another material or blend of materials in the recording sheets of the present invention. Further examples of suitable antistatic materials include those disclosed in copending European patent application EP-A-615,853; copending European patent application EP-A-615,854; copending European patent application EP-A-615,855; copending European patent application EP-A-615,657 filed concurrently herewith; copending European patent application EP-A-615,856 and European patent application EP-A-616,262. Any suitable binder can be employed. Examples of binder materials particularly preferred for the embodiment of the invention wherein a mixture of a binder polymer and antistatic particles are coated onto the substrate in a single layer, and for embodiments wherein it is desired to match the index of refraction of the antistatic particles as closely as possible to the index of refraction of the binder material, preferred binder materials include alcohol soluble polymers, such as those polymers soluble in methanol, including polyacrylic acid, such as #598, #599, #600, #413, available from Scientific Polymer Products, poly (hydroxyalkyl methacrylates), wherein alkyl has from 1 to about 18 carbon atoms, including methyl, ethyl, propyl, butyl, hexadecyl, and the like, including poly(2-hydroxyethylmethacrylate), such as #414, #815, available from Scientific Polymer Products, and poly(hydroxypropylmethacrate), such as #232 available from Scientific Polymer Products, poly (hydroxyalkylacrylates), wherein alkyl is methyl, ethyl, or propyl, including poly(2-hydroxyethyl acrylate), such as #850, available from Scientific Polymer Products, and poly(hydroxypropyl acrylate), such as #851, available from Scientific Polymer Products, poly(vinyl butyral), such as #043, #511, #507, available from Scientific Polymer Products, alkyl cellulose or aryl cellulose, wherein alkyl is methyl, ethyl, propyl, or butyl and aryl is phenyl or the like, including ethyl cellulose such as Ethocel N-22, available from Hercules Chemical Company, poly (vinylacetate), such as #346, #347, available from Scientific Polymer Products, and the like; ketone soluble polymers, such as those polymers soluble in acetone, including hydroxyalkyl cellulose acrylates and hydroxyaryl cellulose acrylates, wherein alkyl is methyl, ethyl, propyl, or butyl and aryl is phenyl or the like, including hydroxyethyl cellulose acrylate, such as #8630, available from Monomer-Polymer and Dajac Laboratories Inc., hydroxyalkyl cellulose methacrylates and hydroxyaryl cellulose methacrylates, wherein alkyl is methyl, ethyl, propyl, or butyl and aryl is phenyl or the like, including hydroxyethyl cellulose methacrylate, such as #8631, available from Monomer-Polymer and Dajac Laboratories Inc., cellulose-acrylamide adducts, such as #8959, #8960, #8961, #8962, available from Monomer-Polymer and Dajac Laboratories, Inc., poly (vinyl butyral), such as #043, #511, #507, available from Scientific Polymer Products, cyanoethylated cellulose, such as #091, available from Scientific Polymer Products, cellulose acetate hydrogen phthalate, such as #085, available from Scientific Polymer Products, hydroxypropylmethyl cellulose phthalate, such as HPMCP, available from Shin-Etsu Chemical, cellulose triacetate, such as #031, available from Scientific Polymer Products, poly (α-methylstyrene), such as #309, available from Scientific Polymer Products, styrene-butadiene copolymers, such as Kraton G-1652, Kraton DX-1150, and Kraton elastomer (such as D1107, G-1657, G-1657/FG1901, D-1101, FG1901, available from Shell Corporation), styrene-butylmethacrylate copolymers, such as #595, available from Scientific Polymer Products, vinyl chloride-vinylacetate-vinyl alcohol terpolymers, such as #428, available from Scientific Polymer Products, chlorinated solvent soluble polymers, such as poly (p-phenylene ether-sulfone) (such as #392, available from Scientific Polymer Products), polysulfones, such as #046, available from Scientific Polymer Products, aromatic ester carbonate copolymers, such as APE KLI-9306, APE KLI-9310, available from Dow Chemical Company, poly carbonates, such as #035, available from Scientific Polymer Products, α-methylstyrene-dimethylsiloxane block copolymers, such as PS 0965, available from Petrarch Systems, dimethyl siloxane-bisphenol A carbonate block copolymers, such as PSO99, available from Petrarch Systems, poly (2,6-dimethyl p-phenylene oxide), such as #126, available from Scientific Polymer Products, poly (2,4,6-tribromostyrene), such as #166, available from Scientific Polymer Products, ethylene-maleic anhydride copolymers, such as #2308, available from Polysciences, Inc., also available as EMA from Monsanto Chemical Co., and the like, as well as blends or mixtures of any of the above. Any mixtures of the above binder materials in any relative amounts can be employed. Examples of binder materials particularly preferred for the embodiment of the invention wherein a binder is first coated onto the substrate, followed by coating the antistatic particles onto the binder include latex polymers, such as (1) cationic, anionic, and nonionic styrene-butadiene latexes (such as that available from Gen Corp Polymer Products, such as RES 4040 and RES 4100, available from Unocal Chemicals, and such as DL 6672A, DL6638A, and DL6663A, available from Dow Chemical Company), (2) ethylene-vinylacetate latex (such as Airflex 400, available from Air Products and Chemicals Inc.), and (3) vinyl acetate-acrylic copolymer latexes (such as synthemul 97-726, available from Reichhold Chemical Inc, Resyn 25-1110 and Resyn 25-1140, available from National Starch Company, and RES 3103 available from Unocal Chemicals; maleic anhydride and maleic acid containing polymers, such as (1) styrene-maleic anhydride copolymers (such as that available as Scripset from Monsanto, and the SMA series available from Arco), (2) vinyl alkyl ether-maleic anhydride copolymers, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, and the like (such as vinyl methyl ethermaleic anhydride copolymer #173, available from Scientific Polymer Products), (3) alkylenemaleic anhydride copolymers, wherein alkylene has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, and the like (such as ethylene-maleic anhydride copolymer #2308, available from Poly Sciences Inc., also available as EMA from Monsanto Chemical Company), (4) butadienemaleic acid copolymers (such as #07787, available from Poly Sciences Inc.), (5) vinylalkylether-maleic acid copolymers, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, and the like (such as vinylmethylether-maleic acid copolymer, available from GAF Corporationas Gantrez S-95), and (6) alkyl vinyl ether-maleic acid esters, wherein alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from 1 to about 20 carbon atoms, more preferably from 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, and the like (such as methyl vinyl ethermaleic acid ester #773, available from Scientific Polymer Products); alcohol soluble polymers, such as those polymers soluble in methanol, including polyacrylic acid, such as #598, #599, #600, #413, available from Scientific Polymer Products, poly (hydroxyalkyl methacrylates), wherein alkyl has from 1 to about 18 carbon atoms, including methyl, ethyl, propyl, butyl, hexadecyl, and the like, including poly(2-hydroxyethylmethacrylate), such as #414, #815, available from Scientific Polymer Products, and poly(hydroxypropylmethacrate), such as #232 available from Scientific Polymer Products, poly (hydroxyalkylacrylates), wherein alkyl is methyl, ethyl, or propyl, including poly(2-hydroxyethyl acrylate), such as #850, available from Scientific Polymer Products, and poly(hydroxypropyl acrylate), such as #851, available from Scientific Polymer Products, poly(vinyl butyral), such as #043, #511, #507, available from Scientific Polymer Products, alkyl cellulose or aryl cellulose, wherein alkyl is methyl, ethyl, propyl, or butyl and aryl is phenyl or the like, including ethyl cellulose such as Ethocel N-22, available from Hercules Chemical Company, poly (vinylacetate), such as #346, #347, available from Scientific Polymer Products, and the like; ketone soluble polymers, such as those polymers soluble in acetone, including hydroxyalkyl cellulose acrylates and hydroxyaryl cellulose acrylates, wherein alkyl is methyl, ethyl, propyl, or butyl and aryl is phenyl or the like, including hydroxyethyl cellulose acrylate, such as #8630, available from Monomer-Polymer and Dajac Laboratories Inc., hydroxyalkyl cellulose methacrylates and hydroxyaryl cellulose methacrylates, wherein alkyl is methyl, ethyl, propyl, or butyl and aryl is phenyl or the like, including hydroxyethyl cellulose methacrylate, such as #8631, available from Monomer-Polymer and Dajac Laboratories Inc., cellulose-acrylamide adducts, such as #8959, #8960, #8961, #8962, available from Monomer-Polymer and Dajac Laboratories, Inc., poly (vinyl butyral), such as #043, #511, #507, available from Scientific Polymer Products, cyanoethylated cellulose, such as #091, available from Scientific Polymer Products, cellulose acetate hydrogen phthalate, such as #085, available from Scientific Polymer Products, hydroxypropylmethyl cellulose phthalate, such as HPMCP, available from Shin-Etsu Chemical, cellulose triacetate, such as #031, available from Scientific Polymer Products, poly (α-methylstyrene), such as #309, available from Scientific Polymer Products, styrene-butadiene copolymers, such as Kraton G-1652, Kraton DX-1150, and Kraton elastomer (such as D1107, G-1657, G-1657/FG1901, D-1101, FG1901, available from Shell Corporation), styrene-butylmethacrylate copolymers, such as #595, available from Scientific Polymer Products, vinyl chloride-vinylacetate-vinyl alcohol terpolymers, such as #428, available from Scientific Polymer Products, chlorinated solvent soluble polymers, such as poly (p-phenylene ether-sulfone) (such as #392, available from Scientific Polymer Products), polysulfones, such as #046, available from Scientific Polymer Products, aromatic ester carbonate copolymers, such as APE KLI-9306, APE KLI-9310, available from Dow Chemical Company, poly carbonates, such as #035, available from Scientific Polymer Products, α-methylstyrene-dimethylsiloxane block copolymers, such as PS 0965, available from Petrarch Systems, dimethyl siloxane-bisphenol A carbonate block copolymers, such as PSO99, available from Petrarch Systems, poly (2,6-dimethyl p-phenylene oxide), such as #126, available from Scientific Polymer Products, poly (2,4,6-tribromostyrene), such as #166, available from Scientific Polymer Products, and the like, as well as blends or mixtures of any of the above. Any mixtures of the above binder materials in any relative amounts can be employed. In the recording sheets of the present invention, both those prepared by coating a mixture of binder and antistatic particles in a single layer onto the substrate and those prepared by first coating a binder onto the substrate and subsequently coating the antistatic particles onto the binder, the antistatic particles can also function as anti-slip components, thereby enhancing the feeding of these sheets through the paper path in an imaging apparatus. Accordingly, while additional anti-slip agents, such as silica particles or the like, can, if desired, be added to the recording sheets of the present invention, such additional additives are not necessary. The coating or coatings on the substrate of the recording sheets of the present invention can be applied to the substrate by any suitable technique. For example, the layer coatings can be applied by a number of known techniques, including melt extrusion, reverse roll coating, solvent extrusion, and dip coating processes. In dip coating, a web of material to be coated is transported below the surface of the coating material (which generally is dissolved in a solvent) by a single roll in such a manner that the exposed site is saturated, followed by the removal of any excess coating by a blade, bar, or squeeze roll; the process is then repeated with the appropriate coating materials for application of the other layered coatings. With reverse roll coating, the premetered coating material (which generally is dissolved in a solvent) is transferred from a steel applicator roll onto the web material to be coated. The metering roll is stationary or is rotating slowly in the direction opposite to that of the applicator roll. In slot extrusion coating, a flat die is used to apply coating material (which generally is dissolved in a solvent) with the die lips in close proximity to the web of material to be coated. Once the desired amount of coating has been applied to the web, the coating is dried, typically at from about 25 to about 100°C in an air drier. Recording sheets of the present invention can be employed in printing and copying processes wherein dry or liquid electrophotographic-type developers are employed, such as electrophotographic processes, ionographic processes, or the like. Yet another embodiment of the present invention is directed to a process for generating images which comprises generating an electrostatic latent image on an imaging member in an imaging apparatus; developing the latent image with a toner; transferring the developed image to a recording sheet of the present invention; and optionally permanently affixing the transferred image to the recording sheet. Still another embodiment of the present invention is directed to an imaging process which comprises generating an electrostatic latent image on a recording sheet of the present invention; developing the latent image with a toner; and optionally permanently affixing the developed image to the recording sheet. Electrophotographic processes are well known, as described in, for example, US-A-2,297,691 to Chester Carlson. Ionographic and electrographic processes are also well known, and are described in, for example, US-A-3,564,556, US-A-3,611,419, US-A-4,240,084, US-A-4,569,584, US-A-2,919,171, US-A-4,524,371, US-A-4,619,515, US-A- 4,463,363, US-A-4,254,424, US-A-4,538,163, US-A-4,409,604, US-A-4,408,214, US-A-4,365,549, US-A-4,267,556, US-A-4,160,257, and US-A-4,155,093. The recording sheets of the present invention can also be used in any other printing or imaging process, such as printing with pen plotters, handwriting with ink pens, offset printing processes, or the like, provided that the ink employed to form the image is compatible with the ink receiving layer of the recording sheet. Specific embodiments of the invention will now be described in detail. These examples are intended to be illustrative, and the invention is not limited to the materials, conditions, or process parameters set forth in these embodiments. All parts and percentages are by weight unless otherwise indicated. EXAMPLE 1 Twenty transparent recording sheets were prepared by a dip coating process (both sides coated in one operation) by providing Mylar® base sheet in cut sheet form 21.6cm x 28cm (8.5 x 11.0 inches) in a thickness of 100 microns and coating the base sheet with a vinyl acrylic terpolymer latex (RES 3103, obtained from Unocal Chemicals), which latex was present in a concentration of 20 percent by weight in water. Subsequent to air drying at 100°C for a period of 30 minutes and monitoring the weight prior to and subsequent to coating, the dried sheets were each coated with 0.4 grams 4 microns in thickness (on each side) of the vinyl-acrylic terpolymer. These dried first coating layers were then overcoated with a solution of tetrabutyl ammonium chloride hydrate (#34,585-7, obtained from Aldrich Chemical Company, mp = 44°C), which solution was present in a concentration of 2 percent by weight in methanol. Subsequent to air drying the two layered two-sided coated transparency sheets at 25°C for a period of 30 minutes and monitoring the weight prior to and subsequent to coating, the dried vinyl-acrylic terpolymer toner receiving layer was overcoated with 0.2 grams, 2.0 microns in thickness (each side) of a low melt antistatic and anti-slip powder layer wherein the particles were less than 1 micron in average particle diameter. These sheets were then fed individually into a Xerox® 1038 black imaging apparatus and images were obtained with an average optical density of 1.35 (black). These images had 96.3 percent of the toner fixed as determined by a 3M Scotch® tape toner lift off test. Additional transparency sheets were prepared by the same process with the binder materials and antistatic particle materials indicated in the Table below, wherein each antistatic material was coated onto the binder layer from a 2 percent by weight solution in methanol and each binder layer was coated onto the substrate as a water-based latex containing 20 percent by weight solids, with the following results: (In the above Table, refractive indices (RI) of the solid materials were calculated based on the refractive index values of their liquid homologs; for example, the RI of 1,3-diaminopropane is 1.4570 and the RI of 1,5-diaminopentane is 1.4582, indicating a 0.0006 increment for each additional -CH 2 - group (source, Aldrich Chemicals). The RI values for the copolymeric binders were calculated as the sum of the RI values of homopolymers of each monomer, weighted for the percentage of each monomer in the copolymer; for example, the RI of polystyrene is 1.59 and the RI of polybutadiene is 1.52, so in a styrene-butadiene copolymer containing 75 percent by weight styrene and 25 percent by weight butadiene, the RI is 1.5375.)

Claims: A substantially transparent recording sheet which comprises (a) a substantially transparent substrate; (b) a binder polymer coated on the substrate; and (c) particles of an antistatic component, said particles being present on at least the surface of the binder polymer coating, characterized in that the antistatic component has a melting point of about 70°C or less. A recording sheet according to claim 1, wherein the binder polymer and the antistatic particles are present as a mixture in a single layer. A recording sheet according to claim 1 or claim 2, wherein the antistatic particles are of an average particle diameter of less than about 5 microns; or wherein the antistatic particles are of an average particle diameter of from about 0.5 to about 5 microns; or wherein the antistatic particles are of an average particle diameter of less than about 1 micron. A recording sheet according to any one of claims 1 to 3, wherein the index of refraction of the binder and the index of refraction of the antistatic component differ by no more than about ±0.01; preferably the index of refraction of the binder and the index of refraction of the antistatic component differ by no more than about ±0.005. A recording sheet according to any one of claims 1 to 4, wherein the antistatic component is selected from the group consisting of (1) benzyl dimethyl tetradecyl ammonium chloride dihydrate, (2) benzyl dimethyl stearyl ammonium chloride monohydrate, (3) cetyl pyridinium bromide monohydrate, (4) dodecyl pyridinium chloride monohydrate, (5) hexadecyl tributyl phosphonium bromide, (6) 1,12-diaminododecane, (7) stearyl tributyl phosphonium bromide, (8) benzyl dodecyl dimethyl ammonium bromide, (9) tetrabutyl ammonium chloride hydrate, (10) 1,8-diamino octane, (11) benzyl cetyl dimethyl ammonium chloride monohydrate, and (12) mixtures thereof. A recording sheet according to any one of claims 1 to 5, wherein the binder is selected from the group consisting of polyacrylic acid, poly (hydroxyalkyl methacrylates), wherein each alkyl has at least one carbon atom, poly (hydroxyalkylacrylates), wherein alkyl has at least one carbon atom, alkyl cellulose, wherein alkyl has at least one carbon atom, aryl cellulose, wherein aryl has at least six carbon atoms, hydroxyalkyl cellulose acrylates, wherein alkyl has at least one carbon atom, hydroxyaryl cellulose acrylates, wherein aryl has at least six carbon atoms, hydroxyalkyl cellulose methacrylates, wherein alkyl has at least one carbon atom, hydroxyaryl cellulose methacrylates, wherein aryl has at least six carbon atoms, poly (vinyl butyral), cyanoethylated cellulose, cellulose acetate hydrogen phthalate, hydroxypropylmethyl cellulose phthalate, cellulose triacetate, poly (α-methylstyrene), styrene-butadiene copolymers, styrene-butylmethacrylate copolymers, vinyl chloride-vinylacetate-vinyl alcohol terpolymers, poly(p-phenylene ether-sulfone), polysulfones, aromatic ester carbonate copolymers, polycarbonates, α-methylstyrene-dimethylsiloxane block copolymers, dimethyl siloxane-bisphenol A carbonate block copolymers, poly(2,6-dimethyl p-phenylene oxide), poly (2,4,6-tribromostyrene), ethylene-maleic anhydride copolymers, and mixtures thereof; or wherein the binder is selected from the group consisting of cationic styrene-butadiene latexes, anionic styrene-butadiene latexes, nonionic styrene-butadiene latexes, ethylene-vinylacetate latexes, vinyl acetate-acrylic copolymer latexes, styrene-maleic anhydride copolymers, vinyl alkyl ether-maleic anhydride copolymers, wherein alkyl has at least one carbon atom, alkylene-maleic anhydride copolymers, wherein alkylene has at least one carbon atom, butadiene-maleic acid copolymers, vinylalkylether-maleic acid copolymers, wherein alkyl has at least one carbon atom, alkyl vinyl ether-maleic acid esters, wherein alkyl has at least one carbon atom, polyacrylic acid, poly (hydroxyalkyl methacrylates), wherein alkyl has at least one carbon atom, poly (hydroxyalkylacrylates), wherein alkyl has at least one carbon atom, poly(vinyl butyral), alkyl cellulose, wherein alkyl has at least one carbon atom, aryl cellulose, wherein aryl has at least six carbon atoms, poly (vinylacetate), hydroxyalkyl cellulose acrylates, wherein alkyl has at least one carbon atom, hydroxyaryl cellulose acrylates, wherein aryl has at least six carbon atoms, hydroxyalkyl cellulose methacrylates, wherein alkyl has at least one carbon atom, hydroxyaryl cellulose methacrylates, wherein aryl has at least six carbon atoms, cellulose-acrylamide adducts, cyanoethylated cellulose, cellulose acetate hydrogen phthalate, hydroxypropylmethyl cellulose phthalate, cellulose triacetate, poly (α-methylstyrene), styrene-butadiene copolymers, styrene-butylmethacrylate copolymers, vinyl chloride-vinylacetate-vinyl alcohol terpolymers, poly(p-phenylene ether-sulfone), polysulfones, aromatic ester carbonate copolymers, polycarbonates, α-methylstyrene-dimethylsiloxane block copolymers, dimethyl siloxane-bisphenol A carbonate block copolymers, poly (2,6-dimethyl p-phenylene oxide), poly (2,4,6-tribromostyrene), and mixtures thereof. A recording sheet according to any one of claims 1 to 6, wherein the layer containing the binder material and the antistatic polymers is from about 3 to about 10 microns in thickness. A recording sheet according to claim 1 or any one of claims 3 to 7, when dependent on claim 1, wherein the binder polymer is present in a first layer and the antistatic particles are present in a second layer coated onto the first layer. A recording sheet according to claim 8, wherein the first layer containing the binder is from about 1 to about 10 microns in thickness and the second layer containing the antistatic particles is from about 1 to about 5 microns in thickness. A process for generating images which comprises generating an electrostatic latent image on an imaging member in an imaging apparatus; developing the latent image with a toner; transferring the developed image to a recording sheet according to any one of claims 1 to 9; and optionally permanently affixing the transferred image to the recording sheet. An imaging process which comprises generating an electrostatic latent image on a recording sheet according to any one of claims 1 to 9; developing the latent image with a toner; and optionally permanently affixing the developed image to the recording sheet.

Inventors: MALHOTRA SHADI L, MALHOTRA, SHADI L.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1994
Main classification: B41M5
IPC codes: G03G7, B41M5, B32B27